Volume 3, Number 6
Dec 1990

Permanence Standards

JCP has two fairly new standards (which they call specifications) for semi-permanent paper:

JCP A25, Heat-set web offset machine finish book JCP A61, High quality acid-free book, smooth-finish They require a minimum pH of 7.0, but do not mention calcium carbonate. Groundwood and unbleached pulp are excluded. The A25 has two strength measures, tensile and burst, while the A61 has only one, burst, but the minimum is two or three times the minimum specified in the A25.

The DIN (German Institute of Standards) has a Paper and Board-Standardization Comittee which has drafted a four-page standard for "Paper and Board Lifespan Classes." This is being circulated for comment. It calls for a minimum tearing resistance (MD) of 50 mN, which is very low, only 1/7 the minimum proposed by the Australian permanence standards committee; but the draft standard says this is put forward as the strength needed by an old document in order to remain suitable for its intended use. It feeds into a formula with five variables or constants, all of which seem to have been invented for the purpose. The document does not say what is wrong with the usual way of writing permanence standards. Accelerated aging is to be done at 80°C and 65% RH, for 6, 12 or 24 days; strength is to be measured by tensile, stretch and tear tests. The data on the test papers that formed the basis for this draft standard are published with critical--very critical--commentary in Das Papier 44, Heft 9, 1990, by Helmut Bansa: "Messmethoden zur Bestimmung der Alterungsbeständigkeit von Paper." The author used the formula on old papers and then aged them, and says he found contradictions. The formula predicted a life of several hundred years, for example, for a groundwood content paper with a pH of 4.0.

Standards Australia has a committee working on a standard for permanent uncoated paper and paperboard. Unlike the DIN committee, it has an even balance of representatives from the paper industry and cultural institutions.